Unity is a lightweight, extensible dependency injection container. This release is a port of Unity 2.0 to Microsoft Silverlight 4.0 and 3.0. Unity addresses issues faced by developers engaged in component-based software engineering. Modern business applications consist of custom business objects and components that perform specific or generic tasks within the application, in addition to components that individually address cross cutting concerns such as logging, authentication, authorization, caching, and exception handling. The key to successfully building such applications is to achieve a decoupled or very loosely coupled design. Loosely coupled applications are more flexible and easier to maintain. Unity help you incorporate this loosely coupled design into your projects.
Download: Unity 2.0 for Silverlight